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make it difficult for plants to extract water from the soil. Soil salinity is a problem in the western <br />United States due to the relatively low precipitation and high evapotranspiration (ET) which <br />allow for the accumulation of salts in the root zone (Soil Improvement Committee, 2002). Plants <br />respond to the average salinity of the root zone and not to the soil salinity of an individual depth <br />(i.e. 0 to 6 inches) of the root zone (Ayers and Westcot, 1985; Casler et al., 1996). <br />In 2011, the author, in conjunction with the Colorado Division of Reclamation Mining and <br />Safety (DRMS) and the United States Office of Surface Mining (OSM) conducted extensive soil <br />testing on the Morgan property. The soil testing data used in the following analysis comes from <br />samples taken of each of the topsoil stockpiles; from undisturbed soils adjacent to the mining <br />operation; and from the 20 acres on the eastern side of the Morgan property were substitute <br />subsoil was previously placed. The soil salinity, as measured by ECe, of the sampled soil <br />material ranges from 2.9 to 4.6 deciSeimens per meter (dS/m)(Figure 1). The lowest ECeof the <br />sampled material is the Barx Lift A soil (undisturbed Lift A material) while the greatest soil <br />salinity is located in the Substitute Subsoil material. The soil salinity of all the soil materials, <br />except the Mixed and Substitute Subsoil, are less than 4.0 dS/m which is the salinity threshold <br />for 100% alfalfa production in soils containing gypsum (Maasand Hoffman,1977; and Ogle and <br />St. John, 2009). The natural soil salinity of the Barx soil series can be as great as 4.0 dS/m <br />according to the USDA-NRCS official soil series descriptions (USDA-NRCS, 2011). <br />Figure 1. Soil EC of soil material at the Western Fuels-Colorado New Horizon Mine. <br />Discussion <br />The increase in soil salinity between the native soil profile (Barx Profile, Barx Lift A and/or <br />Barx Lift B) compared to the stockpiled soil (Lift A, Lift B, andMixed Topsoil) is the focus of <br />questions raised by the Morgans. One potential explanationis that this increase in soil salinity is <br />due to natural processes such as physical and chemical weathering. An alternative explanationis <br />that the increase in soil salinity is due to the repeated application of high salinity mine pit water <br />5 <br />{00136879.1 } <br />